A differential pressure transducer is a device which generates an electrical signal when two fluids at different pressures are applied to the device. The magnitude of the electrical signal may be proportional to the difference between the fluid pressures. For example, the magnitude of the signal may increase as the difference between the fluid pressures increases, thus providing an indication of the magnitude of the difference between the two pressures. The differential pressure transducer is typically permanently fixed within a casing which protects the transducer and channels the fluids to the transducer.
It is frequently necessary to monitor or measure the difference between two high but nearly equal fluid pressures, e.g., a first fluid pressure of 5,020 pounds per square inch (psi) and a second fluid pressure of 5,000 psi. While the difference between the two fluid pressures is small, e.g., about 20 psi, the difference between each fluid pressure inside the casing and standard atmospheric pressure, i.e., about 14.7 psi, outside the casing is very large, e.g., about 5,000 psi. Consequently, the casing must be fashioned from very heavy duty materials to prevent the fluid inside the casing from rupturing the casing. Unfortunately, a heavy duty casing is relatively expensive, so, once the differential pressure transducer permanently fixed within the casing fails, it is necessary to replace both the transducer and the expensive casing.